1999 Cadillac STS Antifreeze leak and window

JSBOND

MEMBER
1999 CADILLAC STS
V8
2WD
AUTOMATIC
140,000 MILES

Have had the car in for an antifreeze leak 3 times; mechanic cannot find the problem. Said he checked head gaskets some way (with some chemical), and ruled that out (already replaced those a few years back). He thought it was related to the water pump, so replaced that. Also, replaced the oil pressure Sending Unit. Then, pulled off the water passage housing to check the 4 main gaskets that bolt the plate to the block, stating "that is where your leak is coming from." But it wasn't. He found a broken/leaking cooling system quick disconnect. Finally, thought I might have got a bad water pump, so replaced that under warranty. I don't seem to lose so much antifreeze on the road, so much as short trips around town, and while it sits afterward. The car does NOT overheat, even going up very steep hills.

Now, the passenger window will go down, but not back up. They replaced the mechanism where the cable is inside the door, noticing NOW it does down very slowly, and even slower back up. Sometimes stopping completely and you have to wait for it a bit, and then it will go the rest of the way. Now they're saying it is some electronic module. The mechanism was nearly $500. And the module to be another $270, but I wanted to run this by the experts first. The window actually went down FASTER BEFORE the repair.

Thanks!

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1 Reply

CARADIODOC

MECHANIC
33,873 POSTS

For an elusive leak, consider adding a small bottle of dark purple dye to the coolant, then search a day later with a black light. The dye will show up as a bright yellow stain that you can follow back to the source. Auto parts stores will have the correct dye for the fluid, and those that rent or borrow tools should have a black light.

For a sluggish window, start by washing the rubber channels with Silicone Spray Lube. Slow movement can be caused by arced switch contacts, or in this case, relay contacts inside a computer module, but road dirt and bug juice in the window channels is also a common cause of slow operation. The Silicone lube will go on like water, evaporate, and leave a film of "slippery" behind.